It’s always subjective, but Perry plastics are probably your best (most historically accurate) option for Zulus, with Empress for their Imperial opponents.
I think the Redoubt Enterprises version of RD is still hard to beat.
And may I add a heartfelt thank you for your guides, which were immensely helpful when I first started out assembling forces for the period.
By coincidence, we’re planning a series of Zulu War games for the coming months, using suitably tweaked TMWWBK (Osprey) rules, which lend themselves to much larger actions than the skirmish level scenarios they appear to be written for.